Gene Transfer of IκBα Limits Infarct Size in a Mouse Model of Myocardial Ischemia-Reperfusion Injury

Abstract

Nuclear factor-κB (NF-κB) plays a central role in myocardial ischemia-reperfusion (MI/R) injury. The inhibitory protein IκBα prevents its activation. We investigated the effects of adeno-associated viral vector-mediated IκBα gene transfer in MI/R injury. Male C57BL/6 mice were randomized to receive a recombinant adeno-associated virus (rAAV) encoding the gene for the NF-κB inhibitory protein IκBα (rAAV- IκBα) or the β-galactosidase gene (a control and inert gene; rAAV-LacZ), both at a dose of 1011 copies. Four weeks later anesthetized animals were subjected to total occlusion (45 minutes) of the left main coronary artery followed by 5 hours of reperfusion. MI/R produced a wide infarct size (IF/area-at-risk = 56 ± 8%; IF/left ventricle = 44 ± 5%) and tissue neutrophil infiltration, studied by means of elastase activity (area-at-risk = 2.5 ± 0.4 μg/gm tissue; infarct area = 2.9 ± 0.6 μg/gm tissue). Furthermore MI/R caused peak message for intercellular adhesion molecule-1 (ICAM-1) in the area-at-risk at 3 hours of reperfusion (1.2 ± 0.4 relative amount of cardiac ICAM-1 mRNA). NF-κB activation was evident at 0.5 hours of reperfusion and reached its maximum increase at 2 hours of reperfusion. rAAV-IκBα injection reduced infarct size (IF/area-at-risk = 19 ± 3%; IF/left ventricle = 10 ± 2%; p < 0.001), blocked NF-κB activation, diminished cardiac ICAM-1 expression (0.4 ± 0.02 relative amount of cardiac ICAM-1 mRNA; p < 0.001), and blunted leukocyte accumulation (area-at-risk = 0.6 ± 0.05 μg/gm tissue; infarct area = 0.4 ± 0.02 μg/gm tissue; p < 0.001). Our data indicate that rAAV-IκBα may be useful for MI/R gene therapy.